Can metric data be an effective tool for galliform skull identification in archaeological contexts?

Galliforms, or game birds, are commonly found in zooarchaeological assemblages but several taxa within the order (e.g. chicken, pheasant and grouse) are difficult to distinguish from one another morphologically. Osteometrics is a tool for understanding skeletal variation in animal populations that has been shown to be useful in distinguishing between closely related genera in galliform post-cranial elements. In this paper, we test whether metrics are also effective in identifying galliform skulls (crania and mandibles) to the genus level. Using osteometric data collected from nine North American gallinaceous genera, we found that size was the greatest source of variation within the order. Several dimensions (greatest height, smallest breadth between orbits and length of incisivum) on the cranium were successful in distinguishing Domestic chicken (Gallus gallus domesticus) from Ring-necked pheasant (Phasianus colchicus), while measurements on the mandible were not very effective in separating closely related taxa. The application of osteometrics to fragmentary bird skulls from an historic era site assemblage in New York was not effective in identifying birds beyond general size-classes even with the aid of morphology and comparative collections. This suggests that previous work identifying fragmentary skull remains to the species level is not accurate, and that more advanced methods need to be developed to identify morphological and metric variation between taxa in these fragmentary elements.